This invention relates to an antimicrobial nonwoven web for personal care absorbent articles, which provides both antimicrobial and odor control properties.
Nonwoven webs used in personal care absorbent articles can harbor bacteria, particularly when in contact with bodily fluids. Some of this bacteria can cause, or help cause skin rash and other discomfort to the wearer of the absorbent article. Some of this bacteria causes odor. It is known to use antimicrobial agents to reduce or prevent bacteria growth. However, antimicrobial agents themselves may contribute to skin rash and other discomfort. Therefore, it is usually not desirable to use an antimicrobial agent which affects the bacteria typically found at or near the surface of the wearer""s skin.
There is a need or desire for antimicrobial nonwoven webs useful in absorbent articles which can prevent or inhibit growth of bacteria, including bacteria found at or near the wearer""s skin, without promoting skin irritation or other discomfort.
The present invention is directed to an antimicrobial nonwoven web useful in personal care absorbent articles. The antimicrobial nonwoven web contains an antimicrobial agent which reduces or prevents bacteria growth without causing harm or discomfort to the wearer""s skin. The antimicrobial agent is a stable halogenated polystyrene hydantoin which does not release the halogen (e.g., chlorine) over time. Polystyrene hydantoin generally contains both an amide nitrogen and an imide nitrogen which can be chemically linked to a halogen (e.g., chlorine or bromine). The inventor has discovered that nonwoven webs treated with chlorinated polystyrene hydantoin are stable, and do not release chlorine, when chlorine atoms are linked entirely to the amide nitrogen sites in the polystyrene hydantoin molecules, and are not linked to the imide nitrogen sites.
The nonwoven web treated with the stable halogenated polystyrene hydantoin can be any of the nonwoven webs used in an absorbent article which are exposed to an aqueous liquid insult. For instance, the nonwoven web may be a cellulose nonwoven web, such as is used in an absorbent core. The nonwoven web may also be a spunbond web, a melt blown web, a bonded carded web, an air laid web, or the like, such as are used in a bodyside liner and/or surge layer of a personal care absorbent article.
The term xe2x80x9cnonwoven fabric or webxe2x80x9d means a web having a structure of individual fibers or threads which are interlaid, but not in a regular or identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, air laying processes, and bonded carded web processes. The term also includes cellulose fiber webs and other absorbent fiber webs formed using various processes, as well as apertured films having openings for passing liquid. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91.)
The term xe2x80x9ccellulose fibersxe2x80x9d refers to fibers from wood, paper, woody plants, and certain non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for instance, cotton, flax esparto grass, milkweed, straw, jute hemp, and bagasse.
The term xe2x80x9cspunbonded fibersxe2x80x9d refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinnerette having a circular or other configuration, with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartmann, U.S. Pat. No. 3,502,538 to Petersen, and U.S. Pat. No. 3,542,615 to Dobo et al., each of which is incorporated herein in its entirety by reference. Spunbond fibers are quenched and generally not tacky when they are deposited onto a collecting surface. Spunbond fibers are generally continuous and often have average diameters larger than about 7 microns, more particularly, between about 10 and 30 microns.
The term xe2x80x9cmeltblown fibersxe2x80x9d means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity heated gas (e.g., air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in diameter, and are generally self bonding when deposited onto a collecting surface.
The term xe2x80x9cmicrofibersxe2x80x9d means small diameter fibers having an average diameter not greater than about 75 microns, for example, having an average diameter of from about 1 micron to about 50 microns, or more particularly, microfibers may have an average diameter of from about 1 micron to about 30 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber. For a fiber having circular cross-section, denier may be calculated as fiber diameter in microns squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns may be converted to denier by squaring, multiplying the result by 0.89 g/cc and multiplying by 0.00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 (152xc3x970.89xc3x970.00707=1.415). Outside the United States the unit of measurement is more commonly the xe2x80x9ctex,xe2x80x9d which is defined as the grams per kilometer of fiber. Tex may be calculated as denier/9.
The term xe2x80x9cpolymerxe2x80x9d includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc., and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term xe2x80x9cpolymerxe2x80x9d shall include all possible geometrical configurations of the material. These configurations include, but are not limited to isotactic, syndiotactic and atactic symmetries.
The term xe2x80x9cabsorbent fibersxe2x80x9d refers to fibers capable of absorbing about 5 to less than 15 times their weight in an aqueous solution containing 0.9 weight percent sodium chloride. The term is intended to include cellulose fibers, but not superabsorbent materials. xe2x80x9cNonabsorbentxe2x80x9d or xe2x80x9cnon-retentivexe2x80x9d fibers are fibers which absorb and retain less than about 5 times their weight in an aqueous solution containing 0.9% by weight sodium chloride.
xe2x80x9cSuperabsorbentxe2x80x9d or xe2x80x9csuperabsorbent materialxe2x80x9d refers to a water-swellable, water-insoluble organic or inorganic material capable, under the most favorable conditions, of absorbing at least about 15 times its weight and, more desirably, at least about 20 times its weight of an aqueous solution containing 0.9 weight percent sodium chloride. The superabsorbent materials can be natural, synthetic and modified natural polymers and materials. In addition, the superabsorbent materials can be inorganic materials, such as silica gels, or organic compounds such as cross-linked polymers.
The term xe2x80x9cpersonal care absorbent articlexe2x80x9d includes without limitation diapers, training pants, swim wear, absorbent underpants, baby wipes, adult incontinence products, and feminine hygiene products.
The term xe2x80x9cmedical absorbent articlexe2x80x9d includes without limitation garments, underpads, bandages, absorbent drapes, and medical wipes.